Calibrating structured-light vision sensor with one-dimensional target

In order to calibrate the three-dimensional measurement model parameters of structured-light vision in situ, a novel approach to easily calibrating a structured-light vision sensor with free-moving one-dimensional target (at least 3 feature-points aligned on a feature-line and one of them chosen as the origin) is proposed. In the camera coordinate frame, the vanishing point of the feature-line can be obtained on the basis of 1D projective transformation, with at least three collinear feature-points on the feature-line, so the direction vector of the feature-line can be determined by joining the projective center and the vanishing point. The camera coordinates of the origin can be computed in accordance with the direction of the feature-line and the known distance between the origin and the other feature-point. The camera coordinates of a control point on the light-stripe can be calculated by the feature-line equation and its distance to the origin which is calculated with its projective coordinates based on 1D projective transformation. The light plane is fitted with at least three nonlinear control points in the camera coordinate frame. The experimental results prove that the proposed approach can achieve the same calibration accuracy as the planar-target-calibration approach under general laboratory conditions. Compared to planar target, 1D target with high accuracy and large dimensions is manufactured more easily and maintained more simply. Moreover, the proposed technique is also important in practice especially when calibrating structured-light vision sensor with large-scale measuring range.